This invention relates to aquarium filtering and aerating systems and, more particularly, to an aquarium power head for drawing water through a riser tube of an aquarium undergravel filter. The power head is effectively a water pump but includes an air inlet for mixing the air with the water stream, thereby aerating the water. A muffler is formed integrally with the housing for silencing sucking-in sounds produced by the air entering the power head.
Aquariums are used widely for housing fish and other aquatic life. In order to provide a proper habitat for the aquatic life, water held within an aquarium tank is generally filtered and aerated to ensure a removal of waste matter and provide an adequate concentration of oxygen. Aeration and filtration of water matter can be combined using the well-known undergravel filter system in which aquarium water is drawn through aquarium gravel spaced off the bottom by a porous plastic plate at the bottom of the tank. The filtered water flows upward through a riser tube and returns to the aquarium. A water pump, generally referred to as a power head, sits on the riser tube and lifts the water up the riser tube and then emits it back to the aquarium. An air passage in the power head causes air to be sucked in as the water passes and the air becomes entrained in the water so that the filtered water returning to the aquarium is now aerated.
Power heads suitable for use with an undergravel filter may be constructed to include a pump having an impeller operated by an electric motor. Water drawn into the power head passes through a water conduit. There is also provided an air-breather conduit which is in flow communication with the water conduit via an air-induction port in a sidewall of the water conduit. By venturi action, the air is drawn from the breather conduit into the flowing water to form a series of bubbles entrained in the stream of water. The motor, the impeller, and both of the conduits are encased within a housing. The housing includes water inlet and outlet ports for the water conduit, and an air inlet port for the breather conduit.
There are a number of problems which arise in the use of existing power heads. One of the problems arises from the shape of the housing of the power head. Typically, the housing is constructed with flat sidewalls. During placement of the apparatus within the aquarium tank, a sidewall of the housing is adjacent to a wall of the aquarium tank. Frequently, a wedge-shaped space develops between the walls of the housing and the tank. A fish swimming in the tank may swim into the space between the housing and a tank wall, and become trapped and suffocated by the narrowing wedge-shaped space.
Another problem arises from the process of sucking in of air into the inlet port. This causes a hissing noise as the air enters. The air then mixing with the water also causes noise. These noises cause the known power heads to be annoying and cause users to dislike their presence in the aquarium. Some power head manufacturers place a tubing at the air inlet with a cup at the end and insert some type of foam in the cut. Absorbent cotton or polyester foam are used, but when compacted they cup the air flow severely. If not compacted, they allow excessive noise. When they get wet, they completely cut off the air supply.
A further problem relates to the support for the power head. Typically, a clamp or holder must be used to retain the power head over the riser tube. The holder must permit adjustment to position the power head properly. Typically, such holders are complex apparatus, which is costly, difficult to operate, and not always aesthetically acceptable.